This invention relates to an electric immersion heater in which an insulated resistive heating element is immersed in the liquid directly, the element being suitably supported and shrouded for protection.
A construction of heater of the aforementioned kind is disclosed in British Patent No. 1,360,334 wherein a resistance wire coated in PTFE is wound around a tubular support element provided with apertures through which liquid may flow. An outer protective housing being provided which is apertured also to allow liquid flow. With a single heater wire element a relatively long length is necessary to achieve a suitable value of resistance with good heat dissipation. This creates difficulties in accommodating the wire length in a manner which affords good heat dissipation into the liquid, and in which minimum contact with the support is made.
An object of this invention is to provide an immersion heater unit in which a heating wire is disposed in a manner affording good liquid flow thereover due to convection and in which the maximum amount of wire surface area is fully in contact with the liquid to be heated.